<template>
      <div style="position: absolute ;width: 100%;top: 0;left: 0 ;padding-top: 35vh ;z-index: 1000">
                      <div style="display: flex;
                                    flex-direction: column;
                                    align-items: center;
                                    justify-content: center;">
                          <div style="display: inline-block ">
                              <a
                                  style=" font-size: 7vh; color: #000000;text-transform: uppercase;letter-spacing: 2px; font-weight: 600;margin-right: 18vw">
                                  知识分享平台
                              </a>

                          </div>
                          <div style="background: linear-gradient(to right, rgba(238,138,110,0.84), rgba(129,155,245,0.72));">
                              <a
                                  style=" font-size: 7vh; color: #000000;text-transform: uppercase;letter-spacing: 2px; font-weight: 600;">
                                  欢迎加入我们
                              </a>
                          </div>
                          <ul style="
                              display: flex;
                          justify-content: center;
                          align-items: center;
                        margin-top: 70px">
                              <li style="list-style: none;">
                                  <a id="btn-" href="#" style="text-decoration: none;
                            padding: 15px 35px;
                            border-radius: 20px;
                        background: rgba(0, 0, 0, 0.25);
                          color: #000000;">立即体验</a>
                              </li>
                          </ul>
                      </div>
                  </div>

</template>

<script>

import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
import * as THREE from 'three'
import { onMounted,onUnmounted } from 'vue'

export default {
  name: 'HomePage',
  setup(){



    let renderer = new THREE.WebGLRenderer({ antialias: true });
    let camera = new THREE.PerspectiveCamera(60, innerWidth / innerHeight, 1, 1000);

    function main(){

      let noise = `
vec4 permute(vec4 x){return mod(((x*34.0)+1.0)*x, 289.0);}
float permute(float x){return floor(mod(((x*34.0)+1.0)*x, 289.0));}
vec4 taylorInvSqrt(vec4 r){return 1.79284291400159 - 0.85373472095314 * r;}
float taylorInvSqrt(float r){return 1.79284291400159 - 0.85373472095314 * r;}

vec4 grad4(float j, vec4 ip){
  const vec4 ones = vec4(1.0, 1.0, 1.0, -1.0);
  vec4 p,s;

  p.xyz = floor( fract (vec3(j) * ip.xyz) * 7.0) * ip.z - 1.0;
  p.w = 1.5 - dot(abs(p.xyz), ones.xyz);
  s = vec4(lessThan(p, vec4(0.0)));
  p.xyz = p.xyz + (s.xyz*2.0 - 1.0) * s.www;

  return p;
}

float snoise(vec4 v){
  const vec2  C = vec2( 0.138196601125010504,  // (5 - sqrt(5))/20  G4
                        0.309016994374947451); // (sqrt(5) - 1)/4   F4
// First corner
  vec4 i  = floor(v + dot(v, C.yyyy) );
  vec4 x0 = v -   i + dot(i, C.xxxx);

// Other corners

// Rank sorting originally contributed by Bill Licea-Kane, AMD (formerly ATI)
  vec4 i0;

  vec3 isX = step( x0.yzw, x0.xxx );
  vec3 isYZ = step( x0.zww, x0.yyz );
//  i0.x = dot( isX, vec3( 1.0 ) );
  i0.x = isX.x + isX.y + isX.z;
  i0.yzw = 1.0 - isX;

//  i0.y += dot( isYZ.xy, vec2( 1.0 ) );
  i0.y += isYZ.x + isYZ.y;
  i0.zw += 1.0 - isYZ.xy;

  i0.z += isYZ.z;
  i0.w += 1.0 - isYZ.z;

  // i0 now contains the unique values 0,1,2,3 in each channel
  vec4 i3 = clamp( i0, 0.0, 1.0 );
  vec4 i2 = clamp( i0-1.0, 0.0, 1.0 );
  vec4 i1 = clamp( i0-2.0, 0.0, 1.0 );

  //  x0 = x0 - 0.0 + 0.0 * C
  vec4 x1 = x0 - i1 + 1.0 * C.xxxx;
  vec4 x2 = x0 - i2 + 2.0 * C.xxxx;
  vec4 x3 = x0 - i3 + 3.0 * C.xxxx;
  vec4 x4 = x0 - 1.0 + 4.0 * C.xxxx;

// Permutations
  i = mod(i, 289.0);
  float j0 = permute( permute( permute( permute(i.w) + i.z) + i.y) + i.x);
  vec4 j1 = permute( permute( permute( permute (
             i.w + vec4(i1.w, i2.w, i3.w, 1.0 ))
           + i.z + vec4(i1.z, i2.z, i3.z, 1.0 ))
           + i.y + vec4(i1.y, i2.y, i3.y, 1.0 ))
           + i.x + vec4(i1.x, i2.x, i3.x, 1.0 ));
// Gradients
// ( 7*7*6 points uniformly over a cube, mapped onto a 4-octahedron.)
// 7*7*6 = 294, which is close to the ring size 17*17 = 289.

  vec4 ip = vec4(1.0/294.0, 1.0/49.0, 1.0/7.0, 0.0) ;

  vec4 p0 = grad4(j0,   ip);
  vec4 p1 = grad4(j1.x, ip);
  vec4 p2 = grad4(j1.y, ip);
  vec4 p3 = grad4(j1.z, ip);
  vec4 p4 = grad4(j1.w, ip);

// Normalise gradients
  vec4 norm = taylorInvSqrt(vec4(dot(p0,p0), dot(p1,p1), dot(p2, p2), dot(p3,p3)));
  p0 *= norm.x;
  p1 *= norm.y;
  p2 *= norm.z;
  p3 *= norm.w;
  p4 *= taylorInvSqrt(dot(p4,p4));

// Mix contributions from the five corners
  vec3 m0 = max(0.6 - vec3(dot(x0,x0), dot(x1,x1), dot(x2,x2)), 0.0);
  vec2 m1 = max(0.6 - vec2(dot(x3,x3), dot(x4,x4)            ), 0.0);
  m0 = m0 * m0;
  m1 = m1 * m1;
  return 49.0 * ( dot(m0*m0, vec3( dot( p0, x0 ), dot( p1, x1 ), dot( p2, x2 )))
               + dot(m1*m1, vec2( dot( p3, x3 ), dot( p4, x4 ) ) ) ) ;

}
  `;

      console.clear();

      let scene = new THREE.Scene();

      camera.position.set(20, 40, 5).setLength(13);
      const targetPoint = new THREE.Vector3(-5, -100, 9);

      renderer.setSize(innerWidth, innerHeight);
      renderer.setClearColor(0xE7E7E7, 1);  // 1 表示不透明度
      document.body.prepend(renderer.domElement);

      let controls = new OrbitControls(camera, renderer.domElement);
      controls.enableZoom = false;
      controls.enableRotate = false;

      let g = new THREE.CylinderGeometry(1, 1, 10, 200, 200, true);
      g.scale(1, 1.5, 1);
      let gu = {
        time: { value: 0 }
      }
      let m = new THREE.MeshBasicMaterial({
        depthTest: false,
        depthWrite: false,
        side: THREE.DoubleSide,
        transparent: true,
        opacity: 0.75,
        onBeforeCompile: shader => {
          shader.uniforms.time = gu.time;
          shader.vertexShader = `
      #define ss(a, b, c) smoothstep(a, b, c)
      uniform float time;
      varying vec3 nView;
      varying vec3 nNor;
      ${noise}

      vec3 getShaped(vec3 p){
        float curve = ss(0., 0.5, uv.y);
        curve += ss(0.5, 1., uv.y) * 2.5;
        p.xz *= 0.75 + curve;
        return p;
      }

      vec3 getNoised(vec3 p){
        float t = time * 0.5;
        float n = snoise(vec4(p * 0.4 - vec3(0, t, 0), 3.14));
        n *= 0.5 + 0.5 * (uv.y);
        p += normal * n;
        return p;
      }

      vec3 rotY(vec3 p, float a){
        float s = sin(a);
        float c = cos(a);
        p.xz *= mat2(c, -s, s, c);
        return p;
      }

      ${shader.vertexShader}
    `.replace(
              `#include <begin_vertex>`,
              `#include <begin_vertex>
        vec3 pos = getNoised(getShaped(position));
        vec3 pos2 = getNoised(getShaped(rotY(position, 3.1415926 * 0.001)));
        vec3 pos3 = getNoised(getShaped(position + vec3(0., 0.001, 0.)));
        transformed = pos;

        vec3 nor = cross(normalize(pos2 - pos),normalize(pos3 - pos));
        nNor = normalMatrix * nor;

      `
          ).replace(
              `#include <fog_vertex>`,
              `#include <fog_vertex>
        nView = normalize(mvPosition.xyz);

      `
          );
          console.log(shader.vertexShader);
          shader.fragmentShader = `
      #define ss(a, b, c) smoothstep(a, b, c)
      varying vec3 nView;
      varying vec3 nNor;
      ${shader.fragmentShader}
    `.replace(
              `#include <color_fragment>`,
              `#include <color_fragment>
        diffuseColor.rgb = mix(vec3(1, 0.375, 0), vec3(0, 0.5, 1), pow(vUv.y, 2.));
        float alpha = ss(0., 0.2, vUv.y) - ss(0.8, 1., vUv.y);
        //alpha = alpha;

        vec3 nor = nNor * (gl_FrontFacing ? 1. : -1.);
        float vAlpha = abs(dot(normalize(nView), nor));

        float angleAlpha = (1. - vAlpha) * 0.9 + 0.1;
        //angleAlpha = pow(angleAlpha, 4.);

        float totalAlpha = clamp(alpha * 0.6  +  angleAlpha * 0.5, 0., 1.) * alpha;
        diffuseColor.rgb += vec3(1) * totalAlpha * 0.1;
        diffuseColor.a *= totalAlpha;
      `
          );
          //console.log(shader.fragmentShader);
        }
      });
      m.defines = {
        "USE_UV": ""
      };
      let o = new THREE.Mesh(g, m);
      o.rotation.z = -Math.PI * 0.25;
      scene.add(o);

      let clock = new THREE.Clock();

      renderer.setAnimationLoop(() => {
        let t = clock.getElapsedTime();
        gu.time.value = t;
        camera.lookAt(targetPoint);
        renderer.render(scene, camera);
      });
    }

    onMounted(() => {
      // 在组件挂载时将 renderer.domElement 添加到 body
      console.log(1)
      document.body.prepend(renderer.domElement);
      main(); // 初始化 Three.js 场景
    });

    onUnmounted(() => {
      // 在组件卸载时从 body 移除 renderer.domElement
      document.body.removeChild(renderer.domElement);
      cleanupThreeJS(); // 清理 Three.js 场景
    });

    function cleanupThreeJS() {
      // 清理 Three.js 场景
      renderer.dispose();
      renderer.forceContextLoss();
    }

    function resizeRenderer() {
      renderer.setSize(window.innerWidth, window.innerHeight);
      camera.aspect = window.innerWidth / window.innerHeight;
      camera.updateProjectionMatrix();
    }

    // 添加事件监听器
    window.addEventListener('resize', resizeRenderer);

    // 初始化时也调用一次
    resizeRenderer();




  }
};


</script>

<style scoped>
html, body {
  height: 100%;
  margin: 0;
  padding: 0;
}
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Poppins', sans-serif;
  scroll-behavior: smooth;
}
</style>